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Chemical Formula | Cu | |||||
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Composition | Copper, commonly associated with iron and silver | |||||
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Variable Formula | (Cu,Fe,Ag) | |||||
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Color | Copper. Tarnishes green, sometimes blue or black. | |||||
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Streak | Copper. Streak shiny. | |||||
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Hardness | 2½ - 3 | |||||
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Crystal Forms and Aggregates |
(Isometric) Usually found as distorted masses or extremely distorted crystals. Crystals are usually cubic or dodecahedral. Octahedral crystals do occur, but are very rare. Also occurs as flattened crystals, scales, dendrites, and wires. | |||||
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Transparency | Opaque | |||||
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Specific Gravity | 8.93 | |||||
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Luster | Metallic | |||||
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Cleavage | None | |||||
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Fracture | Hackly | |||||
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Tenacity | Ductile and Malleable | |||||
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Other ID Marks | 1) Tarnishes. Green tarnish speckled throughout a
specimen, may also be blue or black 2) Very good conductor of electricity (second best; after silver) |
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Other Names |  Native Copper |
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Varieties |  Copper Bloom - Copper with
green and blue tarnish stains speckled throughout. |
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In Group | Native elements ; Metallic elements | |||||
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All About | Copper usually has impurities, but can be found pure. Native copper is found only in small quantities throughout the world, but there are a few areas that are rich in findings, such as the Keweenaw Peninsula in Michigan. Well crystallized specimens are not common, and are very much sought after. The interlocking Copper and Silver masses that are commonly found in the Keweenaw Peninsula are known as "Halfbreeds". | |||||
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Uses | Native Copper was the only source of copper
until the turn of the century, when extraction methods
were improved. The copper ores
are far more abundant than Native Copper, and are
therefore the main source of copper nowadays. Even
though, Native Copper is a sometimes mined as a minor ore
of copper. Copper ranks second for as most-used metal in
the world. The special properties of conductivity, malleability, resistance, and beauty make it so popular. The main
uses of copper are electrical, due to the greatness of
copper's conductivity, which offers the lowest electrical
resistance after silver. Copper is very ductile and can be drawn into very thin wires,
which serves as its primary electrical function. It is
used for electrical machinery such as motors,
electromagnets, generators and communication devices. Copper has been fashioned into ornamental objects and cooking utensils. Coins have been made of copper throughout history. Copper is also used in pigments, insecticides, and fungicides, although it has of lately been largely replaced by synthetic chemicals. Also see the gemstone section on Copper |
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Striking Features | Intense copper color; green, blue, and black tarnish; interesting crystal habit; great malleability and ductility. | |||||
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Popularity (1-4) | 1 | |||||
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Prevalence (1-3) | 2 | |||||
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Demand (1-3) | 1 | |||||
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Distinguishing Similar Minerals |
Copper's distinctive habits distinguish it from all other minerals. | |||||
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Commonly Occurs With |
Calcite, Cuprite, Malachite, Azurite, Silver | |||||
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Noteworthy Localities |
The mines in the Keweenaw Peninsula in Michigan and the surrounding area produce plenty of excellent specimens. Crystals as large as 2 inches (5 cm) have been found there, as well as huge wiry masses and distorted hunks. Ajo, Pima Co., Arizona has produced many well formed specimens. Chessy, France, and several mines in Cornwall, England, have also produced quality specimens. | |||||
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Picture Icon Links |
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Picture Links | 1. Distorted crystal mass of Copper 2. Copper crystals in mass of distorted Copper |
